I will go to light side, which will give me + 3str.
So my question is for attributes that i will get by leveing, and they are exact 5.
Im not sure what is better to spend first 2 Attribute to Constitution and Con to be total - 18, and spend the remaining 3 to Str, and Strength to be total - 19(22 with Light Mastery).

Its not big deal ofc, but im going for perfection.
Also if i spend 2 points to Con, will my chance to hit be good enough with 19 base str? I Play with Flurry and One-Handed Saber with Duelling.

I would go with Constitution if you wish to become tankier but if you want an even higher chance of hit, then i'd put them in strength. Depends on what items you use and their stat bonuses as well. Dexterity might be a good attribute to level up too, because that increases your defense and if that is high enough you may not need as much points into constitution.

I would usually go 10 Strength and 10 Constitution and instead spam points into Dexterity. But because Soldiers have Fortitude and little Reflex, Dexterity doesn't work as well for them as they do for other classes. This is why I usually don't go Soldiers and choose Scouts or Scoundrels instead - Dexterity helps you hit with lightsabers and gives you Reflex, which allows you to dodge. I don't remember having Constitution ever higher than 10, and now I do the same for Strength - mainly because items and lightsaber crystals can amplify your damage enough. But all this rambling doesn't apply as much with Soldiers because, as I said, their Fortitude > Reflex. For your build, I would only go 10 Dexterity; your Constitution and Fortitude are high enough where you have enough Health and Defense to soak damage - making Reflex a waste of points.